My 2004 jaguar s type 3.0 is having restricted performance any idea what could be causing this.

Question

It runs but has no power every time you step on the gas the cars shakes at idel and when on drive

Answer 1

is your engine light on? if so you will need an OBD-II reader to get the code, without a code it is hard to know what is exactly wrong.

I would start by checking for intake leaks, and replacing the spark plugs if you have not done so